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Bloodthirsty Villian


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By: Nicholas Cox

Some like to kill them in cold blood at first sight.
Still few let them go unharmed, mostly due to a squeamish reaction to
distance themselves as far and as quickly as possible. But have you ever
stopped to ponder this monster, the tick?

There are over 800 species of ticks worldwide (1) though only 13 are commonly found in Minnesota. (2)
Most of the ticks found in Minnesota (and worldwide) are known as “hard
ticks” because of the hard shell (or scutum) on the top of their body. (2)
Soft ticks are also found in Minnesota, and can be identified by their
lack of scutum and their very small heads which appear to be missing to
the naked eye. (2) The general life cycle of the tick occurs in four different stages: egg, larvae, nymph, and adult. Female ticks lay
thousands of eggs at one time, and once hatched, the ticks typically
require one meal of blood before molting, or moving on the the next
stage. Some ticks can live up to 30 months without feeding depending on
which stage of life they are in; adults are usually able to last longer
and larvae shorter (although still from 2-15 months!). (3)

In Minnesota and
the surrounding region, there are two
ticks that can be found feeding on humans: the American Dog Tick
(commonly the wood tick) and the Black Legged Tick (commonly the deer
tick). (2) These ticks both survive Minnesota winters underground and
typically take two or more years to complete their life cycle. (2)
They can be found feeding on humans at all life stages; larvae can be
identified by their smaller bodies and their six legs, nymphs are larger
and have eight legs, and adults are the largest also with eight legs.
Each feeding event lasts for a period of days.

 Ticks are important worldwide because they are vectors for disease, transmitting protozoan, rickettsial
and viral disease most problematic to livestock. In Minnesota, the deer
tick is widely known to spread the organisms that cause Lyme disease,
though it spreads less common disease-causing organisms as well. (2)
Wood ticks are known to spread the organism that causes Rocky Mountain
spotted fever in humans, but its occurrence is very uncommon in
Minnesota. (2) The potential for a deer tick bite in Minnesota
is great enough that people who spend any time in forests, tall
grasses, or other deer tick habitat are recommended to take prevention
measures. CCM field crews use multiple defenses, ranging from 20%+ DEET
solutions to tucking pant legs into socks and duct taping to prevent
ticks from getting inside of clothes. Combined with daily (or more
frequently) tick checks, this has shown a very effective technique so
far this year with zero reported instances of Lyme’s symptoms (at this
point I invite everyone to find some wood on which to knock). Some
studies have shown 20% DEET solutions to provide 81%-85% effectiveness
at deterring ticks while a chemical called permethrin
is 89-100% effective. While showing the best results, permethrin is a
bit more high maintenance as it can only be applied as a treatment to
clothing and is only effective on unwashed clothes for up to one month. (3)

Would the world miss the tick?  If my basic ecology
education has taught me anything, the answer to this question is quite
certainly a resounding YES. Population ecology, especially when
considering disease vectors, hosts, and transmission can become very
complicated very quickly. Ticks likely play a role in population control
of the wildlife and livestock with which they’ve co-evolved, and their
elimination or sudden population change could set off an avalanche of
effects unforeseen by the casual observer.  As part of a much more
simple thought, ticks are a major food source for reptiles, birds, and
amphibians. (3)  So next time you find a tick who’s climbed
aboard your ship for a meal, take a second to ponder the wonders of life
and its intricate ecosystems, then proceed as you will.

Disclaimer to potential tick activists: DO NOT allow said tick to enjoy said meal, they don’t need any martyrs.

Sources:

1. The Global Importance of Ticks. F. Jongejan and G. Uilenberg. 

2.Ticks and Their Control. Jeffrey Hahn.

3. Integrated Pest Management Manual: Ticks.  National Park Service.